Earticle

COD can be divided into biodegradable and nonbiodegradable fractions on the basis of biodegradability and the biodegradable COD might be subdivided into readily and slowly biodegradable fractions. These subdivision of COD could influence an the performance of biological nutrient removal(BNR) process and optimization of the treatment plant design. In this study, total COD of municipal wastewater was subdivided into readily and slowly biodegradable COD(Ss and Xs) as well as soluble and particulate inert COD(Si and Xi). The COD fractionation of the municipal wastewater were investigated for the five cities in Chungnam area by nitrate uptake rate(NUR) and flocculation method. Ss fraction were from 16.3 to 27.1 % of the influent COD by NUR method and from 10.2 to 21.6% of the influent COD by flocculation method. Xs fraction were from 16 to 30% of the influent COD by NUR method, the flocculation method could not distinguish between Xs and Xi. Therefore, the specific subdivided COD fractions can be utilized specific parameters for the design of nutrient removal process. A Correlation between NUR method and flocculation method showed R square value of 0.85 therefore Ss value could get easy and fast using flocculation method.